Telephone-exchange system.



H. G. WEBSTER.

TELEPHONE EXGHANGE SYSTEM. APPLIOATION FILED FEB. 23, 1906.

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H. G. WEBSTER. TELEPHONE EXCHANGE SYSTEM.

APPLIOATION FILED 33.23, 1906. i v

Patented Aug. 10, 1909.

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UNITED smrrEs PATENT OEEIOE.

HARRY e. WEBSTER, OF CHICAGO, ILLINOIS, Assieivonio MILO o. KELLOGG, OECHICAGO,

ILLINOIS. I

.TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Aug. 10, 1909.

Application filed February23, 1906. Serial No. 302,581.

T all whom it may concern:

Be it known that I, HARRY G. WEBSTER, a citizen of the United States,and resident of Chicago, county of Cook, and State of Illinois, haveinvented a certain new and useful Improvement in Tele hone-ExchangeSystems, of which the fol owing is a full, clear, concise, and exactdescription.

My invention relates to tele hone exchange systems employing a centralattery for signaling, and particularly to that type adapted for centralbattery transmission in which the switching terminals or spring jacks ofthe lines are constructed each with only two con tact pieces, connectedwith the two line limbs respectively; the connecting plugs beingcorrespondingly provided each with only two contacts, these forming theterminals of link conductors by which the lines are temporarily switchedtogether.

The principal object of my invention is to provide improved means forcontrolling the display of the subscribers calling signal, and a secondobject is to provide improved means for controlling the circuits of thesupervisory signals.

Other objects and advantages of my invention will be apparent to thoseskilled in the art from the following description.

In accordance with my invention, I associate with the line circuit asignal controlling electro-magnet normally under the control of thesubscriber, whereby a call may be initiated at the central office. Themagnet core is provided with a non-magnetic metallic shell or shield,and has two windings differentially connected, one of said windingsbeing included in that portion of a line limb extending to thesubstation and the other winding being included in that portion of thesame line limb extending to the spring jacks. The two windings areconnected at their intermediate point to the central source of current,said connection including an impedance or resistance. The two windingsare preferably concentric windings; that is, wound one outside of theother upon the magnet core, and that winding connected to-' ward thesubstation has a lesser number of turns than the other winding. Themagnet is preferably in the form of a relay magnet controlling thecircuit of an incandescent lamp signal, although I am not limited tosuch construction, as itwill be obvious that it might be a magnetcontrolling directly a tively low resistance,

one arrangement, it

mechanical signal or target. The magnet is so designed that when circuitis closed through the first mentioned winding by the removal of thetelephone at the substation, it will be sufiicientlyenergized to causethe display ofits signal. Cord connecting apparatus is provided, adaptedupon the insertion of the connecting plug to complete a circuit from thecentral battery through the last mentioned winding of the magnet inopposition to that through the first mentioned winding and the armatureadjustment and relative number of turns are such that the currentthrough this opposing winding will sufiiciently weaken or reverse the.energization of the magnet to allow its armature to be retracted andefiace the calling signal as long as the plug remains in the jack.The'two windings are serially included in one side of the talkingcircuit but being wound over a non-magnetic shell as well asdifferentially connected and preferably of relado not interfere withtransmission nor unduly unbalance the talking circuit.

I will describe my invention more fully by reference to the accompanyingdrawings forming a part of this specification, in which Figure 1illustrates two completeline circuits together with appropriate cordconnecting apparatus all organized. in accordance With the preferredform of my invention, and Fig. 2 illustrates a modification of the linecircuit arrangement of Fig. 1 and an alternative cord connectingstructure adapted for use therewith.

Referring first to Fig. 1, the subscribers apparatus is represented asconsisting of a telephone hook switch it, signal bell 1), condenser c,transmitter t, and receiver 7, the bell'and condenser being in normalbridge of the two line limbs and the receiver and transmitter being in anormally open circuit which is closed upon the GIGVEL LIOII Of the hookswitch. Although I have shown but will be understood by those skilled inthe art that various other arrangements of the subscribers apparatus maybe used, and I do not confine myself to the particular arrangementillustrated.

Under normal conditions, thereceiver being upon its switch-hook, thecondenser c prevents a normal flow of current from the battery G at thecentral office overthe telephone line limbs. lVhen, however, thesubscriber removes his telephone from its hook, thus. establishing arelatively low resistance path for current through the transmitter t 5and receiver 1", the signal controlling relay 4 at the central officewill be energized by V the flow of current from the battery 0 throughwinding 15 of impedance coil 3, Winding 7 of relay 4, limb 1 of thetelephone 10 line, through the substation, back to the central officeover limb 2 and thence through winding 14 of impedance coil 3 to thereturn or ground side of the battery C. This cur rent will energizerelay 4, causing the attrac- 15 tion of its armature, thus closing acircuit for signal lamp '5. Upon observing the calling signal, theoperator will insert the left and or answering plug P of the cordcircuit into a s ring jack 1O of the line, corres ond- 2o ing to t ecalling signal, thus causing the tip and sleeve contact pieces of theplug to engage respectively with the corresponding contact pieces of thespring jack. The ti contact pieces of the plug and spring 'jacl;complete a circuit for the flow of current from battery C, which maybetraced as follows z-from the active terminal of battery C, throughconductor relay 20, strand 16, spring jack 10, winding 6 of relay 4 andso thence through winding 7 and the line limbs to the return side of thebattery over the circuit previously traced. It will be seen that thecurrent through winding 6 of .relay 4 now opposes that through winding 7and 35 the energization of relay 4is thus sufliciently reduced to allowthe retraction of its armature 30 and the extinguishment of lamp 5.Supervisory relay 20 'is at this time energized. The engagement of thesleeve con- 40 tact pieces of the lug and spring jack has meanwhileestablished a circuit which may be traced from the active terminal ofthe battery-C through conductor 35, the winding of relay .40, strand 18plug and jack 0011- .tacts and thence through winding 14 of 'impedance 3to the return side of the battery. This circuit causes the energizationof relay 40 and by the attraction of its armature, lamp 22 is connectedto conductor 32 which 5-0 now stands open at the armature of relay 20..VVere the hook switch at substation A nowdepressed by the replacing ofthe receiver r, the consequent interruption of the circuit of the linelimbs would cause the deenergization-of relay 20 and allow its armatureto be retracted closing the circuit of lamp 22 and causingits-illumination.

U on securing from the subscriber the number of the line desired, inthis case at substation B, the operator tests in the usual way byapplying the tip of her calling lug O to the sleeve of a multiple jack-10 of t is desired line. The tip being normally at the same potentialas the jack sleeve contacts, no eflect is producedif the line is idle.If,'how

ever, the line be connected for conversation at some other spring jack,a flow of current will result when the test is made, which may be tracedfrom the active terminal of battery C through conductor 35 and relay 40or 41 of that cord which is already connected with the line, thencethrough its strand 18 or 19 to the sleeve of the multiple jack at whichconnection exists, over limb 2 to-the jack at which the test is made,thence through the I normally closed contacts of the relay 41, and thewinding of relay 34 to the return side of the batter The relay 34 is atest relay of relatively high resistance and its energization by acurrent flowing over the path just 5 traced causes the attraction of itsarmature, thus including the winding 27 of the operators induction coilin circuit with the battery C giving the customary click which indicatesthat the line is busy. Finding the line idle, 3 the operator inserts thecalling plug 0 and actuates her ringing key g, in the usual man.- ner.Current now flows from generator G through strand 19, limb 2, thesubstation condensers and bell b, limb 1, windings 7 and 97 6 of relay4, and thence through strand 17 and resistance 38 to the return side ofthe generator through the battery C or the circuits connected with thisbattery. The current through relay 4 at this time is of oppositedirection in its two windings, and while some portion of the currentwill be diverted from winding 6 to the path through Windin g 15 ofimpedance 3, the relay will not be suihciently energized to cause theattraction or 1 vibration of its armature. The non-magnetic shelhuponthe relay core provides additional means for preventing the actuation ofthe relay armature at this time. Upon the restoration of the ringingkey, a circuit 10; for relay 41 is completed similar to that previouslytraced for relay 40. The conseuent attraction of armature 47 of thisrelay isconnects the high resistance test relay 34 from the tip strandand completes the oil- 11c cuit of this strand 17 to relay 21 andcondenser (Z. Likewise the attraction of armature 42 of relay 41completes a circuit to cause the illumination of the supervisory lamp 23whiclrmay be traced from the active terminal of battery C throughconductor 35, lamp 23, armature 42, conductor 33, and the contacts ofrelay 21, (which is at this time deenergized) to the return side of thebattery. When the subscriber answers, the elevation of his hook. switchit allows current to flow from conductor 35 through relay 21, strand 17,and winding 6 of relay 4; and uniting with current flowing throughwinding 15, thence through winding 7 ,limb 1, receiver 1 transmitter t,and to therreturn side of the battery through limb 2 and winding 14 ofimpedance 3. The armature of relay 21 is thus attracted, opening thecircuit of lamp 23 and the current which now flows through the theoperator understands that conversation.

is finished and removes the connection.

Fig. 2 visory signals associated with the link conductor have theircircuits completed over a ortion of the talking circuit of the cord andline and the line relay 4 has its windings and contacts so arranged thatwhen the relay is partially energized, its armature will assume anintermediate position. Referring to the drawing it will be seen that theinsertion of a plug into a jack of a line not in use will result in theestablishment of a circuit from battery C through conductor 36, lamp 23,strand 19, limb 2 and to the return side of the battery throughresistance 9 and impedance 14, the resistance 9 being relatively low ascompared with that of the impedance coil. The current flowing over thispath will be sufficient to cause the illumination of lamp 23 as long asrelay 21 remains denergized. When the subscriber closes circuit at thesubstation, current will flow from conductor 36 through relay 21, strand17, windings 6 and 7 and to the return side of the battery through limbs1 and 2, and the resistance 9 in multiple with impedance 14;

and a relatively small current will also flow to line from battery Cthrough the impedance 15 to the point intermediate of the windings 6 and7. The first mentioned current will energize relay 21, thus interruptingthe circuit of lamp 2S and will partially energize relay 4 through theunequal o posing effect of its two windings. This wil cause its armature8 to be attracted to its intermediate position against the spring stop43, thus the low resistance connection to.

removing earth of limb 2, through resistance 9, this now being thecondition required for conversation.

When a subscriber initiates a call, the current flowing through winding7 being at this time unopposed, the relay 4 is energized to its greaterextent causing the complete at traction of its armature 8 to close thecircuit of the line lamp 5, and upon the insertion of the answering plugthe opposing current through winding 6 reduces the energization of therelay to its partial value, allowing the armature to return to itsintermediate posi tion and extinguishing the lamp. Referring differsfrom Fig. 1 in that the super-- to the busy test it will be seen thatupon the initial actuation of the listening key k in answering a call,the testing tip of the plug 0 is connected through a portion of strand17 and spring 25 of the listening key, to the test winding 27 of theoperators set S, and that the lower terminal of this winding isconnected to the return side of the battery as is the sleeve of themultiple jacks. Under normal conditions, therefore, no click will resultwhen testing in the usual way. If, however, the line circuit tested bein use, the potential of the sleeve or test terminal of the multiplejacks of the line tested will be raised above that of the return side ofthe battery either by current flowing through a lamp 22 or 23 and strand18 or 19 of the busy cord circuit or through relay 20 or 21, strand 16or 17 and the limbs of the busy line, thus causing a click to be givenin the o erators set when such busy line is tested. hen the plug isinserted, the restoration of the listening key disconnects the testwinding 27 and reestablishes the normal circuit of strand 17 at contact29. When the subscriber answers, the energization of relay 21 andconsequent attraction of armature 24 closes a circuit around the breakcontrolled by the listening key at contact 29, thus preventing asubseuent interruption to the talking circuit s ouldthe operator actuateher key while the subscribers are in conversation. The resistance 28 isso proportioned with relation to the resistance of impedance 15 andwinding 6 that whenthe ringing key g is actuated to call a subscriber,the relay 4 will be partially energized, thus removing the connectionthrough the low resistance 9 and preventing the display of the line lampat this time. The structure of Fig. 2 operates in other res ects as thatof Fig. 1, and needs no further escription.

Assuming the battery 0 tohave a potential of 40 volts, 1 find that goodresults can be secured by making the ratio of turns in windings 7 and 6of relay 4 or 4 as three is to five, and that winding 14 may have aresist ance of two hundred ohms, Winding a resistance of five hundredohms, relay or 20 a resistance of two hundred ohms and relay aresistance of five hundred ohms, for subscribers lines of averagelength; but 1 do not limit myself to these specific resistances orturns. The armature adjustment of relay 4 or 4' is preferably one inwhich there is a relatively wide air gap between the core and thearmature and in which the armature has a relatively small range ofmotion.

It will be understood that the battery C or C may be one and the sameand that the various grounds indicated may be connections to thegrounded side of the battery or the ofiice return.

It will be apparent that various modifications may be made in thestructures illussignal, means cluded in the l trated without departingfrom the spirit and scope of my invention, and that my invention may beembodied in numerous other organizations than those shown. I, therefore,do not wish to be limited to the specific disclosure, but aim to coverby the terms of the appended claims all such modifications andembodiments.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is 1. A telephone exchange system comprising a telephone lineterminating at an exchange, a signal controlling electro-magnet havingtwo 0 posing windings serially included in the l ine, a source ofcurrent and a resistance in bridge of said line from a pointintermediate of said windings, means under I the control of a subscriberfor closing a circuit through one winding to energize said magnetsuificiently to cause the display of its signal, means for including theother winding in series with said first mentioned winding, and in shuntof said resistance whereby said energization is reduced to an amountinsufficient to cause such display, and a second signal controllingelectro-magnet associated with the line by the closing of said shuntcircuit.

2. A telephone exchange system comprising .a' telephone line terminatingat an exchange, a signal controlling electro-magnet having two opposingwindings serially inine, a source of current and a resistance in bridgeof said line from a point intermediate of said windings, means under thecontrol of a subscriber for closing a circuit through one winding toenergize said magnet suiiiciently to cause the display of its forincluding the other winding in series with said first mentioned winding,and in shuntof said resistance whereby said energization is reduced toan amount insufficient to cause such display, and a signal controllingelectro-magnet included in said shunt circuit and responsive to saidfirst mentioned means.

3. A telephone exchange system compr sing a telephone line terminatingat an ex change, a signal controlling electro-magnet having two 0 posingwindings serially included in the ine, a source of current and aresistance in bridge of said line from apoint intermediate of saidwindings, means under the control of a subscriber for closing a circuitthrough one winding to energize said magnet sufficiently to cause thedisplay of its signal, means for including the other winding in serieswith said first mentioned winding and in shunt of said resistance,whereby said energization is reduced to an amount in- I SllfilOlGIlt tocause such display, a second signal, and means forutilizing the currentin the shunt circuit in the control of said second signal.

4. A telephone system cemprisinga telephone line extending between twostations, I means for establishing a conversational circult over saidline, a signal controlling relay having two energizing windings included111 one limb of the talking circuit thus established and havingcontactsadapted to occupy three operative positions, means under tiecontrol of one station for actuating said relay t by completing acircuit through both of its windings to cause its contacts to occupy oneof said positions, and means under the coni trol of the other stationfor actuating said relay to cause it to occupy another of saidpositions.

5. A telephone system com rising a telephone line extending from a su)station to an exchange, a link-circuit for making connection to saidline, means for holding conversation over said line and link-circuit, asignal controlling relay having two energizing windings included in onelimb of the talking circuit thus established and having contactsadaptedto occupy three operative positions, I means under the control ofthe subscriber for actuating said relay to cause its contacts to occupyone of said operative positions, and means under the control of theoperator for actuating said relay by completing a circuit through-bothof its windings to cause its contactsto occupy another of saidpositions. I 6. A telephone system comprising a telephone line extendingfrom a substation to an exchange, a link-circuit for makingconnection tosaid line, a signal controlling relay having two energizing windingsincluded serially in one limb of said line and having contacts adaptedto occupy three operative positions, a source of current bridged betweenthe line limbs at a point intermediate of said windings, means under thecontrol of the subscriber for completing a circuit through one of saidrelay windings to cause said relay contacts to occupy one of saidoperative positions, and means under the control of the operator'forcompleting a circuit for said relay to causesaid contacts to occupyanother of said positions.

7. A telephone system com rising a telephone line extending from a sustation to an. I exchange, a link-circuit for making connection to saidline, means for holding conversa- /ti0n over said line and link circuit,a signal controlling relay having two energizing windings included inone limb of the talking circuit thus established and having contactsadapted to occupy three operative positions, [a source of currentconnected in bridge from a point intermediate of said windings to the iopposite limb and having its pole adjacent to said latter line limbgrounded, a resistance included in a-branch extending from saidlatterline limbthrough normal contacts of said I relay, and supervisoryapparatus included in branches extending-fromthe live pole of saidl=battery to the opposite link-circuit strands.

8 A telephone system coin rising a telephone line extending from a sustation to an exchange, a link-circuit for making connection to saidline, means for holding conversation over said line and link-circuit, asignal controlling relay having two energizing windings includedserially in one limb of said line, a source of current connected inbridge from a point intermediate of said windings to the opposite linelimb and having its pole adjacent to said latter line limb grounded, andsupervisory apparatus included in branches extending from the live poleof said source to the strands of said link-circuit.

9. A telephone system comprising a telephone line extending in two linelimbs be tween two stations, a connection terminal for said line havingcontacts for each of said limbs, a two-strand link-circuit andconnecting plug for establishing connection with said line limbs throughsaid connection terminal contacts, a signal controlling relay having twoenergizing windings included in one limb of said telephone line andhaving contacts adapted to occupy three operative positions, means underthe control of one station for actuating said relay to cause itscontacts to occupy one of said positions, and means under the control ofthe other station for actuating said relay by closing a circuit throughboth of its windings and one set of plug and jack contacts to cause itto occupy another of its positions.

10. A telephone system comprising a telephone line extending in twolimbs from a substation to an exchange, a connection terminal for saidline having contacts for each of said limbs, a two strand link-circuitand connecting plug for establishing connection with said line limbsthrough said connection terminal contacts, means for holdingconversation over said line and link-circuit, a signal controlling relayhaving two energizing windings included in one limb of the talkingcircuit thus established and having contacts adapted to occupy threeoperative positions, means under the control of the subscriber foractuating said relay to cause its contacts to occupy one of saidoperative positions, and means under the control of the operator foractuating said relay by closing a circuit through both of its windingsand one set of plug and jack contacts to cause the contacts of saidrelay to occupy another of said positions.

11. A telephone system comprising a telephone line extending between twostations, a signal controlling relay individual to said line and havingtwo windings serially connected in one limb of said line, means fornormally closing a circuit from one of said stations through one only ofsaid relay windings to alter the operative condition of said relay, andmeans jointly controlled at said stations for causing a flow of currentin series through both windings to further alter the operative conditionof said relay.

12. A telephone system comprising a telephone line connecting asubstation with the exchange, a signal controlling relay for said linehaving a pair of windings serially included iii circuit with one limb ofsaid line,

cooperating switching means at the substation and the exchange jointlycontrolling a flow of current in series through said relay to alter theoperative condition thereof, and means normally responsive to saidswitching means at the substation to close a circuit through one only ofsaid relay windings to produce a different operative condition of saidrelay.

13. A telephone system comprising a telephone line extending from asubstation to the exchange, a connection terminal at the exchange, aline relay having two windings connected in series in one limb of saidtelephone line at a point intermediate of a 0011- tact of saidconnection terminal and the substation, a signal, means controlled atthe substation for causing a flow of current through one winding of saidrelay to display said signal, and operators connection means forconnection with said terminal adapted to cooperate with saidfirst-mentioned means to establish a current flow in series through saidwindings and said line limb to efiace said signal.

14. A telephone system including a tele phone line extending from asubstation to the exchange, a line relay for said line with a signalcontrolled thereby, said line relay having two windings connected inseries in one limb of said telephone line, means controlled at thesubstation for causing a flow of current through one of said windingsonly to display said signal, an operators link-circuit and a source ofcurrent connected therewith arranged for connection with the limb ofsaid telephone line including said windings in series to cause a flow ofcurrent thiiough both said windings to efi'ace said signa 15. Atelephone system including a telephone line, a signal actuating relaytherefor, two windings for said relay connected in one limb of saidline, means for normally causing a flow of current over said line limbthrough one only of said windings to operate said relay, and means forcausing a flow of current over said line limb in series through bothwindings to change the operative condition of said relay.

In witness whereof, I hereunto subscribe my name, this 19th day of Feby.1906.

HARRY G. WEBSTER.

Witnesses:

